Ambulatory medical devices, such as drug delivery systems and patient monitoring systems, are used in the therapy of various diseases or medical disorders, such as diabetes mellitus, pulmonary hypertension, thalassemia, and chronic pain. Many such devices are adapted to be carried by the user, for example, by means of a belt clip or harness, in the user's clothing pocket, or attached to the user's body or clothing.
A common drug delivery system includes a tubing arrangement to deliver medication to a user cutaneously or subcutaneously. For example, ambulatory infusion pumps are used in delivering a prescribed medication, such as insulin, to a user. In one form, these devices comprise a relatively compact pump housing adapted to receive a syringe or reservoir carrying a prescribed medication for administration to the user through infusion tubing and an associated catheter or infusion set.
The external infusion pump may include a small drive motor connected via a suitable transmission assembly for motor-driven advancement of a reservoir piston to administer the medication to the user. Programmable controls can operate the drive motor continuously or at periodic intervals to obtain a closely controlled and accurate delivery of the medication over an extended period of time. Such infusion pumps are used to administer insulin and other medications, with exemplary pump constructions and systems being shown and described in U.S. Pat. Nos. 4,562,751; 4,678,408; 4,685,903; 5,080,653; 5,097,122; 6,248,093; 6,362,591; 6,554,798; and 6,555,986, which are incorporated by reference herein.
External infusion pumps of the general type described above have provided significant advantages and benefits with respect to accurate delivery of medication or other fluids over an extended period of time. The infusion pump can be designed to be extremely compact as well as water resistant, and may be carried by the user, for example, by means of a belt clip or harness, in the user's clothing pocket, or attached to the user's body or clothing. As a result, important medication can be delivered to the user with precision and in an automated manner, without significant restriction on the user's mobility or lifestyle, including in some cases the ability to participate in water sports.
Due to their small size and portability, ambulatory medical devices can be subjected to a number of external conditions that may adversely affect their performance. For example, external infusion pumps can sustain an occlusion in the delivery tubing. Some pumps have alarm systems designed to detect and indicate pump malfunction or nondelivery of the medication as a result of occlusions. There exists, nevertheless, a need for further improvements in these ambulatory medical devices, particularly with respect to providing warnings or system operational changes in response to external conditions that may affect medical device performance.